Fan vs Conventional Oven Temperature: The Complete Guide

How the two ovens actually differ

A conventional oven heats the air and leaves it more or less still. Hot air rises, so the top shelf runs hotter than the bottom, heat creeps into food slowly from the surface, and every conventional oven develops its own hot spots that experienced bakers learn to work around. A fan oven adds a fan behind the heating element that keeps the air moving constantly. The temperature evens out across the whole cavity, and — just as important — the moving air strips away the thin layer of cooler air that clings to the surface of food, so heat transfers measurably faster. That faster transfer is the whole story: a fan oven at the same dial setting effectively cooks harder than a conventional one.

There is a side effect worth knowing. Moving air also carries moisture away from surfaces more quickly. That is wonderful for crisping skin and browning roast potatoes, but it means delicate batters can form a crust before they have finished rising, and uncovered dishes dry out a little faster. Neither oven is "better" in the abstract — they are different tools, and good recipes assume one or the other.

Fan vs conventional oven temperatures: the 20-degree rule

The standard conversion is simple: for a fan oven, reduce the recipe's conventional Celsius temperature by 20 degrees. In Fahrenheit terms that is a reduction of about 36°F. A cake written for 180°C conventional bakes at 160°C fan; a roast written for 220°C goes in at 200°C fan. American recipes rarely mention fan at all — their Fahrenheit figures are written for conventional ovens, so apply the same reduction after converting to Celsius, exactly as we describe in converting a recipe to grams and Celsius.

Two limits matter. First, many modern British recipe books already print both figures — if the book says "180°C (fan 160°C)", use its numbers rather than your own maths. Second, some manufacturers calibrate their fan ovens to need only a 10-degree reduction; your oven manual outranks any general rule, including this one. Either way, fan ovens finish a little sooner, so start checking delicate bakes five minutes before the recipe's earliest time. Our oven temperature converter handles all four scales instantly when you are converting on the fly.

Fan vs conventional oven temperature conversion table

Is 160°C fan the same as 180°C conventional?

Yes — that is exactly the 20-degree rule in action. 160°C fan, 180°C conventional, 350°F and Gas Mark 4 are four ways of asking for the same cooking heat, which is why this is the row of the table most bakers use every week.

When the fan setting helps

Reach for the fan when you want even heat and crisp surfaces. Roast vegetables and potatoes brown on all sides instead of only where they touch the tray. Two or three trays of cookies, sausage rolls or mince pies bake at genuinely the same rate, so batch baking stops being a shelf-swapping exercise. Skin-on chicken and pork crisp properly. Frozen convenience food, written for fan ovens more often than not, cooks evenly from corner to corner. Fan also helps low, slow drying — meringue bases held at a low temperature, oven-dried tomatoes, herbs — because the moving air carries released moisture away instead of letting it linger.

When conventional is better

Switch the fan off for anything fragile. Light sponges can dome, lean or crack when the crust sets before the rise finishes — a "windswept" top is the classic fan-oven fault. Soufflés dislike the blast for the same reason. Custards, crème brûlée and delicate flans prefer still air, which sets them smoothly without a skin. Meringues can be blown about, browned unevenly and dried too hard. Artisan bread baked in the open oven benefits from conventional heat for the first part of the bake, when steam needs to linger around the loaf for a glossy, crisp crust; the fan works against that steam. If your oven only offers fan, do not despair — drop the temperature an extra 5 to 10 degrees for delicate bakes and position the tin away from the direct airflow.

Gas ovens, briefly

Gas ovens use the Gas Mark scale — Gas 4 is 180°C, Gas 6 is 200°C, and each full mark is roughly 13 to 14 degrees higher than the last. The flame sits at the bottom, so a gas oven is naturally hotter at the top than the bottom, even more uneven than a conventional electric oven, and it adds water vapour to the cavity as it burns. That humidity is kind to roasts and bread. Treat Gas Mark figures as conventional temperatures when converting, use the table above, and remember that the middle shelf is the safest place for cakes until you know your oven's personality.

Frequently asked questions